Aerial and aerial mounting arrangement



Jan. 17, 1939. E. H. TRUMP AERIAL AND AERIAL MOUNTING ARRANGEMENT FiledOct. 24, 1956 \NVENTOR E H TRU M P BY *5 9 ZWM ATTORNEY Patented Jan.17, 1939 UNITED STATES PATENT OFFICE AERIAL AND AERIAL MOUNTINGARRANGEMENT Application October 24, 1936, Serial No. 107,342

In Great Britain October 24, 1935 8 Claims.

This invention relates to aerial and aerial mounting arrangements andhas for its object to provide an improved aerial mounting arrangementsuitable for use upon vehicles, for example, upon tanks. Morespecifically, the invention seeks to provide an aerial mountingarrangement which can be satisfactorily employed without serious risk ofdamage upon a vehicle which may be required to travel over such roughground that the aerial may be subjected to mechanical violence not onlydue to vibration and varying wind pressure but also due to collisionwith obstructions.

According to this invention an aerial is car-- ried from a vehicle bymeans of one or more springs which support the said aerial but willallow it to be moved away e. g. by collision with an obstruction, fromits normally supported position and return it to said normally supportedposition afterwards.

Preferably the spring support for the aerial is constituted by twohelical coil springs, one spring being a closely wound spring withconsiderable residual tension and the other (which is prefer- 26 ablyinside the first spring) being a second helical spring stretched underheavy tension and secured between the two ends of the outer spring.Preferably also the aerial itself is of relatively flexible structureand is supported so as to be 80 normally in the same straight line asthe spring mounting means therefor.

In cases where a very light, small aerial only about four or five feetin length is required to be mounted above a vehicle, the said aerial may35 be mounted quite simply by means of a helical spring one end of whichis attached to a convenient point on the vehicle and the other end ofwhich is attached to the aerial and forms its only support. In generalit will be preferable 4 for the lower end of the aerial and the upperend of the supporting spring to coincide and for the axes of the springand aerial (when in normal position) to be in the same straight line.

This simple form of spring mounting is, how- 5 ever, only satisfactoryfor relatively short and light aerials and when longer and heavieraerials are to be employed a multiple-spring support arrangement, suchas that described below and illustrated purely schematically in theaccom- 50 panying drawing should be adopted.

In the generally preferred construction in accordance with thisinvention and illustrated in the accompanying drawing the aerial ismounted upon a spring mounting constituted by two heli- 55 cal springs,I, 2, one inside the other, the outer spring I being closely wound withconsiderable residual tension and the inner spring 2 being stretchedunder heavy tension as shown. The provision of the inner spring may beregarded as equivalent to providing an outer spring with 5 an increasedresidual tension. The outer spring I is carried by means of a suitableinsulator 3 from the roof 4 of the tank or other vehicle, the lead-inconductor 5 passing through said insulator to the inside of the vehicle.A flexible l0 conductor 6 electrically short circuits the springmounting so that the high frequency currents induced in the aerial donot have to pass through the spring. The conductor 6 should be sodesigned and fitted that, in normal use, it never 15 touches the spring.Lead 5 may be secured to the end of conductor 6 as by a screw M.

The aerial itself is in the same straight line with the normallongitudinal spring direction and, as illustrated the said aerial ismade after 20 the manner of a large tubular metal fishing rod comprisinga plurality of tubes 1 of different diameters (the upper tubes beingsmaller) fitted into one another. This gives a very light and flexibleconstruction. A cord 8 or the like is fixed at one end to the topsection or tube of the aerial and passes down inside the tubes to abobbin 9 firmly fixed to the aerial and coaxial with it. The other endof the cord is fixed by means of the grub screw ID to the bobbin leavinga loop of cord. This loop is wound upon the bobbin until only a smallbight or V is left and this is then slipped over one of four evenlyspaced pegs (not shown) provided on the bobbin to receive it. When thecord has been tightened in this way the aerial is mounted in positionthe bobbin being then covered over as shown by being inserted in thehousing formed in the mount and indicated by the broken line H. The pegsfor retaining the V or final bight of cord are of such length that thereis only a small clearance between the tops of the pegs and the interiorof the housing so that, when the bobbin is in position in the housingthere is no room for the bight to slip off its peg. Thus the cord whichis normally tight, assists in holding the aerial tubes together. Whenthe cord loop is unwound the aerial tubes can be pulled apart to theextent of a few inches and the aerial folded up to occupy a small space,the cord preventing the loss of any aerial tube. In the event of anaerial tube being damaged the end of the loop can be released byremoving the grub-screw l0 and the aerial can now be dismantled and anew tube fitted. The aerial, with its bobbin and cord,

is fixed in position on the spring mounting in any convenient manner. Inthe example given the housing H fits within a bore of a supporting capH? which is secured to the upper end of the springs l, 2.

With the aerial construction illustrated, if only the top of the aerialis struck by an obstruction, the aerial itself will probably bendsufficiently to prevent damage although in any case the springsupporting means will yield, if necessary.

The spring or springs: employed in carrying out the present inventionmay be arranged to be adjustable as to tension so that in any giveninstallation upon a vehicle there will be a range of adjustment topermit of the installation being adjusted to the best resilience oryielding power.

In place of providing an insulator between the spring mounting and thevehicle, an insulator may be provided between the spring mounting andthe aerial. I

The invention enables aerials to be carried upon vehicles, such astanks, without serious risk of damage to the aerial and withoutpermitting any undesirably large mechanical vibrations r oscillations ofthe aerial in normal circumstances.

Having now particularly described and ascertained the nature of myinvention and in what manner the same is to be performed I declare thatwhat I claim is:

1. An antenna installation for a vehicle comprising, a plurality ofaxially aligned tubular metallic members of successively decreasingdiameter, said members being adapted to be assembled to form a hollowrod, a cord passing through said member, one end of said cord beingattached to the small end of the rod, means connected to the member atthe large end of the rod for gripping said cord, said last named meansbeing arranged to hold the cord taut to thereby hold the members inposition, a supporting member secured to said vehicle, an outer springsecured to said supporting member and being closely wound with residualtension, an inner spring stretched under tension, and means forconnecting the large end of the rod to the outer portions of saidsprings.

2. An arrangement as described in claim 1 characterized by that thesupporting member is formed of insulation material, and means areprovided for securing said member to a portion of said vehicle and bythat said spring is tensioned to maintain the rod in a substantiallyvertical position.

3. An arrangement as described in claim 1 characterized by that thegripping means is operable to loosen the cord sufficiently to permittaking down the antenna rod.

EDWARD HERBERT TRUMP.

